RCTIME - BASIC Stamp Command Reference
Page 258
•
BASIC Stamp Programming Manual 2.0b
•
www.parallaxinc.com
Charge time = 4 x 220 x (0.1 x 10
-6
) = 88 x 10
-6
So it takes only 88 µs for the cap to charge/discharge, meaning that the 1
ms charge/discharge time of the example is plenty.
A final note about Figure 5.29: You may be wondering why the 220
Ω
resistor is necessary at all. Consider what would happen if resistor R in
Figure 5.29a were a pot, and were adjusted to 0
Ω
. When the I/O pin went
high to discharge the cap, it would see a short direct to ground. The 220
Ω
series resistor would limit the short circuit current to 5V/220
Ω
= 23 mA
and protect the BASIC Stamp from damage. (Actual current would be
quite a bit less due to internal resistance of the pin’s output driver, but you
get the idea.)
Demo Program (RCTIME1.bs2)
' This program shows the standard use of the RCTIME instruction measuring an RC
' charge/discharge time. Use the circuit in the RCTIME description (in the manual)
' with R = 10 k pot and C = 0.1 µf. Connect the circuit to pin 7 and run the program.
' Adjust the pot and watch the value shown on the Debug screen change.
'{$STAMP BS2} 'STAMP directive (specifies a BS2)
Result VAR WORD 'Word variable to hold result.
Again:
HIGH 7 'Discharge the cap
PAUSE 1 'for 1 ms.
RCTIME 7, 1, Result 'Measure RC charge time.
DEBUG CLS, DEC Result 'Show value on screen.
GOTO Again
2
e
2
sx
2
p
2
NOTE: This is written for the BS2
but can be used for the BS2e,
BS2sx and BS2p also. Locate the
proper source code file or modify
the STAMP directive before
downloading to the BS2e, BS2sx or
BS2p.
N
OTES ABOUT
220
Ω
RESISTER IN
THE
RC
CIRCUITS
.
Содержание BASIC Stamp 2e
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Страница 90: ...BUTTON BASIC Stamp Command Reference Page 88 BASIC Stamp Programming Manual 2 0b www parallaxinc com...
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Страница 128: ...FREQOUT BASIC Stamp Command Reference Page 126 BASIC Stamp Programming Manual 2 0b www parallaxinc com...
Страница 196: ...NAP BASIC Stamp Command Reference Page 194 BASIC Stamp Programming Manual 2 0b www parallaxinc com...
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Страница 214: ...OWOUT BASIC Stamp Command Reference Page 212 BASIC Stamp Programming Manual 2 0b www parallaxinc com...
Страница 216: ...PAUSE BASIC Stamp Command Reference Page 214 BASIC Stamp Programming Manual 2 0b www parallaxinc com...
Страница 226: ...POLLMODE BASIC Stamp Command Reference Page 224 BASIC Stamp Programming Manual 2 0b www parallaxinc com...
Страница 232: ...POLLOUT BASIC Stamp Command Reference Page 230 BASIC Stamp Programming Manual 2 0b www parallaxinc com...
Страница 236: ...POLLRUN BASIC Stamp Command Reference Page 234 BASIC Stamp Programming Manual 2 0b www parallaxinc com...
Страница 240: ...POLLWAIT BASIC Stamp Command Reference Page 238 BASIC Stamp Programming Manual 2 0b www parallaxinc com...
Страница 262: ...RCTIME BASIC Stamp Command Reference Page 260 BASIC Stamp Programming Manual 2 0b www parallaxinc com...
Страница 274: ...RUN BASIC Stamp Command Reference Page 272 BASIC Stamp Programming Manual 2 0b www parallaxinc com...
Страница 310: ...SEROUT BASIC Stamp Command Reference Page 308 BASIC Stamp Programming Manual 2 0b www parallaxinc com...
Страница 324: ...STOP BASIC Stamp Command Reference Page 322 BASIC Stamp Programming Manual 2 0b www parallaxinc com...
Страница 340: ...ASCII Chart Page 338 BASIC Stamp Programming Manual 2 0b www parallaxinc com...
Страница 342: ...Reserved Words Page 340 BASIC Stamp Programming Manual 2 0b www parallaxinc com...
Страница 346: ...Conversion Formatters Page 344 BASIC Stamp Programming Manual 2 0b www parallaxinc com...